Bi-Directional 12v Analogue Panel Voltmeter. DC.
+ or - 15v range (full scale deflection)
Simply wire across the power terminals or the track to measure the voltage available.

Bi-directional means you don't need to worry about getting the polarity correct - the needle swings in either direction - reverse/forward  voltage will be displayed.

Width 64 mm
Height 56 mm
Depth 52 mm
Exact dimension on diagram - please see photographs

Supplied with nuts.

* ALSO listed Bi-directional Ammeter 2a range.
If you would like to buy both, put them in your basket and request an invoice for discounted postage.